As I recall, the key to a successful pinewood derby car is the installation of the wheels. The four plastic wheels are each held on by a single nail which acts as the axle. You have to make sure that nail goes in nice and straight to maximize the vehicles efficiency. And always lubricate the wheels at the axle with graphite.

My pinewood derby cars used rubber wheels and we used 3-N-1 oil on them to make them go faster. What a mess. Oil and grease everywhere.